patch 9.0.1673: cannot produce a status 418 or 503 message

Problem:    Cannot produce a status 418 or 503 message.
Solution:   Add err_teapot().

runtime/doc/builtin.txt

@@ -154,6 +154,7 @@ digraph_getlist([{listall}])	List	get all |digraph|s
 digraph_set({chars}, {digraph})	Boolean	register |digraph|
 digraph_setlist({digraphlist})	Boolean	register multiple |digraph|s
 echoraw({expr})			none	output {expr} as-is
+err_teapot()			Number	produce error 418
 empty({expr})			Number	|TRUE| if {expr} is empty
 environ()			Dict	return environment variables
 escape({string}, {chars})	String	escape {chars} in {string} with '\'
@@ -2176,6 +2177,14 @@ echoraw({string})					*echoraw()*
 <		Use with care, you can mess up the terminal this way.
 
 
+err_teapot([{expr}])					*err_teapot()*
+		Produce an error with number 418, needed for implementation of
+		RFC 2325.
+		If {expr} is present and it is TRUE error 503 is given,
+		indicating that coffee is temporarily not available.
+		If {expr} is present it must be a String.
+
+
 empty({expr})						*empty()*
 		Return the Number 1 if {expr} is empty, zero otherwise.
 		- A |List| or |Dictionary| is empty when it does not have any

src/errors.h

@@ -1037,6 +1037,8 @@ EXTERN char e_missing_argument_str[]
 	INIT(= N_("E417: Missing argument: %s"));
 EXTERN char e_illegal_value_str[]
 	INIT(= N_("E418: Illegal value: %s"));
+EXTERN char e_im_a_teapot[]
+	INIT(= N_("E418: I'm a teapot"));
 EXTERN char e_fg_color_unknown[]
 	INIT(= N_("E419: FG color unknown"));
 EXTERN char e_bg_color_unknown[]
@@ -1270,6 +1272,8 @@ EXTERN char e_is_not_file_or_writable_device[]
 	INIT(= N_("is not a file or writable device"));
 EXTERN char e_str_is_not_file_or_writable_device[]
 	INIT(= N_("E503: \"%s\" is not a file or writable device"));
+EXTERN char e_coffee_currently_not_available[]
+	INIT(= N_("E503: Coffee is currently not available"));
 	// E504
 EXTERN char e_is_read_only_cannot_override_W_in_cpoptions[]
 	INIT(= N_("is read-only (cannot override: \"W\" in 'cpoptions')"));

src/evalfunc.c

@@ -45,6 +45,7 @@ static void f_did_filetype(typval_T *argvars, typval_T *rettv);
 static void f_echoraw(typval_T *argvars, typval_T *rettv);
 static void f_empty(typval_T *argvars, typval_T *rettv);
 static void f_environ(typval_T *argvars, typval_T *rettv);
+static void f_err_teapot(typval_T *argvars, typval_T *rettv);
 static void f_escape(typval_T *argvars, typval_T *rettv);
 static void f_eval(typval_T *argvars, typval_T *rettv);
 static void f_eventhandler(typval_T *argvars, typval_T *rettv);
@@ -1881,6 +1882,8 @@ static funcentry_T global_functions[] =
 			ret_number_bool,    f_empty},
     {"environ",		0, 0, 0,	    NULL,
 			ret_dict_string,    f_environ},
+    {"err_teapot",	0, 1, 0,	    NULL,
+			ret_number_bool,    f_err_teapot},
     {"escape",		2, 2, FEARG_1,	    arg2_string,
 			ret_string,	    f_escape},
     {"eval",		1, 1, FEARG_1,	    arg1_string,
@@ -3922,6 +3925,33 @@ f_environ(typval_T *argvars UNUSED, typval_T *rettv)
 #endif
 }
 
+/*
+ * "err_teapot()" function
+ */
+    static void
+f_err_teapot(typval_T *argvars, typval_T *rettv UNUSED)
+{
+    if (argvars[0].v_type != VAR_UNKNOWN)
+    {
+	if (argvars[0].v_type == VAR_STRING)
+	{
+	    char_u *s = tv_get_string_strict(&argvars[0]);
+	    if (s == NULL || *skipwhite(s) == NUL)
+		return;
+	}
+
+	int err = FALSE;
+	int do_503 = eval_expr_to_bool(&argvars[0], &err);
+	if (!err && do_503)
+	{
+	    emsg(_(e_coffee_currently_not_available));
+	    return;
+	}
+    }
+
+    emsg(_(e_im_a_teapot));
+}
+
 /*
  * "escape({string}, {chars})" function
  */
@@ -6456,6 +6486,14 @@ f_has(typval_T *argvars, typval_T *rettv)
 		1
 #else
 		0
+#endif
+		},
+	{":tearoff",
+// same #ifdef as used for ex_tearoff().
+#if defined(FEAT_GUI_MSWIN) && defined(FEAT_MENU) && defined(FEAT_TEAROFF)
+		1
+#else
+		0
 #endif
 		},
 	{NULL, 0}

src/testdir/test_functions.vim

@@ -30,10 +30,13 @@ func Test_has()
     call assert_equal(1, or(has('ttyin'), 1))
     call assert_equal(0, and(has('ttyout'), 0))
     call assert_equal(1, has('multi_byte_encoding'))
+    call assert_equal(0, has(':tearoff'))
   endif
   call assert_equal(1, has('vcon', 1))
   call assert_equal(1, has('mouse_gpm_enabled', 1))
 
+  call assert_equal(has('gui_win32') && has('menu'), has(':tearoff'))
+
   call assert_equal(0, has('nonexistent'))
   call assert_equal(0, has('nonexistent', 1))
 
@@ -86,6 +89,17 @@ func Test_empty()
   call assert_fails("call empty(test_unknown())", ['E340:', 'E685:'])
 endfunc
 
+func Test_err_teapot()
+  call assert_fails('call err_teapot()', "E418: I'm a teapot")
+  call assert_fails('call err_teapot(0)', "E418: I'm a teapot")
+  call assert_fails('call err_teapot(v:false)', "E418: I'm a teapot")
+
+  call assert_fails('call err_teapot("1")', "E503: Coffee is currently not available")
+  call assert_fails('call err_teapot(v:true)', "E503: Coffee is currently not available")
+  let expr = 1
+  call assert_fails('call err_teapot(expr)', "E503: Coffee is currently not available")
+endfunc
+
 func Test_test_void()
   call assert_fails('echo 1 == test_void()', 'E1031:')
   call assert_fails('echo 1.0 == test_void()', 'E1031:')

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1673,
 /**/
     1672,
 /**/